Hitting Jupiter at speeds of about 130,000 miles an hour, the pieces of Comet Shoemaker-Levy 9 create shock waves that can heat atmospheric gases in their path up to 50,000 degrees F. and leave holes sometimes as large across as the diameter of Earth.
The pieces probably don't penetrate deeper than about 40 miles before being stopped and crushed. The energy released then drives powerful fireball eruptions.
Even though the fragments hit beyond Jupiter's horizon as viewed from Earth, the fireballs rise high enough to be seen by telescopes. The remaining nine fragments are due to strike July 21 and 22.